1. Field of the Invention
The present invention relates to pallets of the type which support goods thereon for storage and shipping. The present invention also relates to a method and apparatus for making cross-members from recyclable corrugated paper board and assembling these members into a pallet with the strength of wood.
2. Description of the Prior Art
Pallets for many years have been made completely of wood primarily due to the strength of wood and the possible reusability of wooden pallets. However, wooden pallets are heavy and expensive and are not easily disposed of after they are damaged beyond repair or cannot be reused because of size or design. The critical shortage of landfill space in the most populous states has resulted in the refusal to accept unwanted wooden pallets. An additional hazard with wooden pallets is the nails used in their construction. As damage occurs to the pallet, protruding and/or exposed nail points and heads can cause damage to goods placed thereon as well as injury to those persons handling the pallets. It is estimated that the grocery trade alone loses 2 billion dollars per year from damage to wooden pallets, purchasing and return costs, repairs, storage, landfill costs, product damage, etc. Other problems include pallet and product contamination, product spillage, insect infestation of the wood and the need for Class A or new pallets for certain goods, i.e. foodstuffs, due to FDA regulations. These problems, the decreasing supply of readily available slow growing hard wood, and the related increasing cost of lumber have led to the development of pallets made from other light-weight, relatively inexpensive material, such as corrugated paperboard from fast growing soft wood trees. Where only 9 wooden pallets can be made from a single tree, the same tree can be used to produce 25-33 corrugated pallets. Two such types of corrugated pallets are illustrated by structures shown in U.S. Pat. Nos. 4,936,229 and 4,378,743.
Pallets made from corrugated paperboard are lighter in weight than pallets made from wood, are easily disposed of, and are eventually recyclable into boxes or additional pallets. Prior art corrugated pallets have been limited in the loads they can carry, however, primarily due to limited beam strength and certain inherent weaknesses in construction. Such pallets may be stored fully loaded in a rack system, stored without any support while loaded, or be lifted in cantilever fashion on short forks of a fork lift, thus, beam strength is critical.
One type of design known in the art for corrugated paperboard pallets with greater strength characteristics is a grid structure. However, to maintain the cost effectiveness of corrugated paperboard pallets in heavy load applications, the design of the pallets has to be uncomplicated enough to allow for a high speed automated assembly process, which is normally the slowest part of production. An automated process is disclosed in U.S. Pat. No. 4,792,325. In order to provide increased strength in corrugated paperboard pallets and to design the pallets to maintain this increased strength through its life cycle, the runners and stringers have been made with complicated structures requiring expensive machinery to assemble. Such a design for a corrugated paperboard pallet is disclosed in U.S. Pat. No. 4,979,446. The cost of the automation machinery for such designs can be upwards of $500 M and such machinery is limited in production to approximately 100-150 pallets per hour. Thus, while corrugated paperboard pallets have been designed to handle greater loads, their structures have become more complicated, resulting in an increased cost of production.
Even with the relatively recent improvements however, prior art pallets are still of insufficient strength for many applications and inadequate in certain critical areas of the pallets. For example, pallets of the grid-type design have cutouts in cross members for receiving the tines of the forklift. These lifting points which receive the tines are inherently weaker and can be snapped by the forklift tines or broken under load. Therefore, there is a need for a stronger more resilient pallet that avoids the above-mentioned problems, that use less material and are less expensive to manufacture and which require less machinery cost for production and assembly.